Chop the chocolate chips as finely as possible for even melting.

Place 5 ounces of chopped semisweet chocolate in a microwave-safe bowl and microwave on defrost setting in 15-second intervals, stirring in between, until melted.

Add remaining chocolate pieces and stir until mostly melted; cool to about 85°F.

Reheat the melted chocolate in microwave for 15 seconds to make it fluid for molding.

Use a basting brush or spoon to coat the inside of silicone molds with chocolate, applying two thin coats.

Clean up excess chocolate with a knife or straight edge.

Refrigerate mold for 3-5 minutes until chocolate sets.

Gently pop out the chocolate shells from the mold.

Spoon hot cocoa mix and mini marshmallows into half of each sphere.

Warm the rim of each half on a plate briefly to melt the edges.

Seal the spheres by pressing the melt rim of one half onto the other.

Melt white chocolate in piping bag and drizzle over the filled spheres for decoration.